Improvement in projectiles



B. B. HOTCHKISS.

PROJECTILES.

Patented Nov. 14,1876.

Noumea.

mm cw m THE GRAPHIC CO-N-Y BENJAMIN B. HOTOHKISS, OF NEW YORK, N. Y.

IMPROVEMENT IN PROJECTILES.

Specification forming part of Letters Patent No. 184,286, dated November14, 1876; application filed September 29, 1876.

To all whom it may concern.-

Be it known that I, BENJAMIN B. HoToH- KISS, of New York city, in theState of New York, temporarily residing in Paris, France, have inventedcertain new and useful Improvements relating to Projectiles, of whichthe following is a specification:

My improvements apply to projectiles for breech-loading rifle-guns, ofall sizes, in which there is a belt or packing of softer metalenveloping a body of cast-iron or other different material. In commonwith other projectiles of this class, I supply a belt or packing ofsufficiently large diameter to fill, or about fill, the rifled grooves,and allow the belt to take the impression of the rifling on entering therifled portion of the piece. This allows projectiles of the rightcaliber to be used in pieces having various numbers and widths ofgrooves.

It seems to be necessary to the best working that the belt or packingshall have considerable width, so as to take hold of each land, notmerely at a single point in the middle or rear of the projectile, butalong a considerable extent of the surface. There are objections to theuse of an extremely soft metal for the packing. It is best for generalpractice in iron guns to use a tolerably hard brass; but the impressingof the grooves of the gun into a broad packing of brass imposes greatresistance to the motion and wear on the gun.

I have devised a cheap and ready means of reducing the extent ofbearingsurface, while leaving itdistribnted along a considerable lengthof the projectile.

The following is a description of what 1 consider the best means ofcarrying out the invention.

The accompanying drawings form a part of this specification.

Figure 1 is an elevation of a projectile with a central longitudinalsection of the packingbelt in the condition it is placed in the gun.Fig. 2 represents the same in the condition it assumes in the act ofmoving forward into the rifled grooves. Fig. 3 is a section of a portionof the same on a larger scale. It shows more plainly the form which Igive to the front face of the forward ridge.

Similar letters of reference indicate corre sponding parts in both thefigures.

A is the body of the projectile, of ordinary cast-iron, which I haverepresented as equipped with a separate conical point, but which,instead thereof, may have any ordinary or suitable fuse-plug or thelike. B is the packingbelt, of good width, and compressed inward at thefront and rear edges, by suitable dies, not represented, so as to engagefirmly with the shoulders at the front and rear edges of the packingseatA. This packing-seat is formed with four or other desired number ofrings, a, which rings are either cast sumciently perfect, or areafterwards finished to exactly the diameter desired, to hold the packingbelt out to the proper extent to fill the rifled grooves or take aproper hold therein. Between these rings or ridges a the packingseat ismore depressed, as indicated by a.

When the gun is discharged. the gases resulting from the combustion ofthe powder flow forward at an immense pressure in the thin annular spacebetween the projectile and the interior of the gun. Practically, none ofthis gas gets between the belt and the body of the projectile, but allpasses on the exterior of the belt, forcing the packing inward againstthe body. The brass is thereby compressed inward, and assumes thecondition shown in Fig. 2. Thus conditioned, the projectile movesforward into the rifled part of the piece, and the lands of the gun areimpressed, not on the entire surface of the pack: ing, but only on theridges, which extend around in packing over and accurately conforming tothe ridges or rings at. These rings are distributed so as to afford theproper support to both ends of the projectile.

In case of very long projectiles I propose to divide the packing-beltinto two parts, leaving an unpacked space between, or, in other words,to employ two or more packing-belts, one before the other. But in suchcase, as with a single belt, I form each with the alternate ridges anddepressions in the seat for the packing, and apply the packing as aplain ring, allowing it to be molded to the seat in the act of firing,as above described.

My experiments indicate that a very moderate amount of bearing-surfaceproperly distributed is sufficient. About the proportions shown in thefigures I believe to be the best.

I esteem it especially important that the foremost ridge shall begradually tapered from the front, as best shown in Fig. 3. Theresistance of the air is materially lessened by making this angle small.4

In Fig. 3 the dotted line m m indicates the extent to which the packingis impressed in entering the rifled portion of the gun.

It will be observed that all those portions of the packing over thedepressions a stand within the diameter of the lands, and remainungrooved.

My invention allows the use of ch aply made and easily applied packings.It may be desirable in some or all cases to turn the ridges a and thedepressions a; but this may be done at the same time that the generalexterior of the projectile is treated, and will increase the labor orcost but little, if at all.

The packing-rings, made as plain cylinders,

may be simply pressed inward at the front and rear edges, and no furthercare is necessary. If preferred, the packing may be pressed into thedepressions by dies.

The thin packing-ring B is made to present,

by-myinventiou, substantially the same ridged surface on its exterior asa thicker packing, after being elaborately grooved around in a lathe orotherwise; but the expense is much less.

I claim as my invention- A projectile for rifle pieces, having ridges aand depressions a in that portion of the main body A beneath the packingB, in combination with such packing as and for the purposes hereinspecified.

In testimony whereof I have hereunto set my hand this 26th day ofSeptember, 1876, in the presence of two subscribing Witnesses.

B. B. HOTGHKISS. Witnesses:

THOMAS D. STETSON, A. HENRY GENTNER.

